I mean, humans can detect magnetic fields as well. There's even languages without relative egocentric positions like left/right, only north south east west. Given all that, I don't think it's out there that dogs sense it and like being aligned when they're trying to poop.
The predominance of geographic directions in Guugu Yimithirr has nothing to do with magnetic sensing; humans know what north and south are from sun positions and memory.
https://www.sciencemag.org/news/2019/03/humans-other-animals...
https://en.wikipedia.org/wiki/Guugu_Yimithirr_language